Combination of virtual screening, machine learning, molecular dynamics simulations and sensory evaluation to discover novel umami peptides from fermented Atlantic cod

The aim of this study was to explore the effect of fermentation with Lactobacillus helveticus Lh191404 on the umami characteristics of Atlantic cod and to elucidate the umami mechanism of the peptide. Post-fermentation significant increases in sweet amino acids (Threonine (Thr), Serine (Ser), Proline (Pro), Glycine (Gly), Alanine (Ala)) and umami amino acids (Aspartic acid (Asp), Glutamic acid (Glu)) enhanced the palatability and umami intensity of surimi. The calculated taste activity value showed Glu as the highest at 2.598, indicating that umami was the most prominent taste after the Atlantic cod fermentation. A new approach was constructed to batch screen high abundance umami peptides. Combined with Nano Liquid Chromatography Tandem Mass Spectrometry (nLC/MS-MS), virtual screening and machine learning identified four highly abundant umami peptides (WGDL, FDDLP, VAQWR, and YGESDL). Molecular docking and molecular dynamics simulations determined that they stably bind to the receptor proteins through hydrogen bonding and electrostatic interactions, with Asp108, Arg151, and Arg277 as the key active amino acids. Sensory evaluation and electronic tongue confirmed that the screened peptides were all umami peptides and the umami intensity was consistent with the simulation results. This study not only revealed that Lactobacillus helveticus Lh191404 enhanced the taste of fermented Atlantic cod by releasing high abundance umami peptides but also provided a novel approach for identifying umami peptides from fermented marine foods.